Sankar, the Intel(R) Core(TM) i5-2500K Processor supports the power limit registers but they might be locked by the BIOS.
Check the Lock Bit described on page 14-23 of volume 3B of the Software Developer’s Manual located at the following website: http://download.intel.com/products/processor/manual/253669.pdf
You can use third party software applications to change these settings but we do not recommend their use and we cannot be held responsible for any damage caused by using or installing 3rd party tools.
I have a motherboard based on Z77 chipset that supports overclocking. I read the msr registers and made sure that the lock bit is not set. However, the power limit feature is still not working.
I try to set a new power cap (lower than the native) using the power limit registers. But the experiments show that the program runs at regular performance (It is supposed to be running at reduced performance after the power cap). I am not sure why this feature isn't working.